But a new report released by the World Bank on Monday honed in on the problem of internal displacement, finding that as many as 140 million people in three densely-populated, developing regions might be forced by climate change to migrate within their countries' borders by 2050. It is the first report to focus on the impact of climate change on intra-country migration specifically, The Guardian reported.

According to the report's worst-case-scenario prediction, Sub-saharan Africa could see as many as 86 million internal migrants, South Asia could see up to 40 million, and Latin America could see 17 million.

The climate-change effects most likely to force migration will be drought, crop failure, sea level rise, and increased storms. But the report also found that swift action on the part of governments to limit greenhouse gas emissions in time and develop plans to help populations in vulnerable areas could reduce the number of migrants by 100 million.

"We have a small window now, before the effects of climate change deepen, to prepare the ground for this new reality. Steps cities take to cope with the upward trend of arrivals from rural areas and to improve opportunities for education, training and jobs will pay long-term dividends. It's also important to help people make good decisions about whether to stay where they are or move to new locations where they are less vulnerable," Word Bank Chief Executive Officer Kristalina Georgieva said in the release of the report.

The report also offers case studies of how governments and non-governmental organizations might plan effectively for migration or help populations live sustainably in rural areas.

Bangladesh, a low-lying country where agriculture is vulnerable to floods and salinization, could end up accounting for one third of South Asia's climate migrants. The Word Bank highlighted the case of Monoara Khatun, who left her village of Kurigram due to flooding, moved to the capital city of Dhaka, and enrolled in the World Bank's NARI project, which provides women with training, accommodation and work placement. The program allowed her to earn enough to support herself and her family, and represents an example of the type of project that could help urban centers prepare for an influx of vulnerable newcomers.

For an example of a program that could help people in rural areas find climate-resilient opportunities, the World Bank held up sustainable forestry programs like one in Oaxaca, Mexico. Because of the program, 26-year-old Javier Martinez was able to stay in his home and grow the carpentry business he runs with his brother.

"At the forest level there is employment, in businesses there is employment, so there is not a strong need to go away, because in the community there is a wide range of opportunities," Martinez told the World Bank.

Sixteen-year-old climate action leader Greta Thunberg stood alongside European Commission President Jean-Claude Juncker Thursday in Brussels as he indicated—after weeks of climate strikes around the world inspired by the Swedish teenager—that the European Union has heard the demands of young people and pledged more than $1 trillion over the next seven years to address the crisis of a rapidly heating planet.

In the financial period beginning in 2021, Juncker said, the EU will devote a quarter of its budget to solving the crisis.

A new study reveals the health risks posed by the making, use and disposal of plastics. Jeffrey Phelps / Getty Images

With eight million metric tons of plastic entering the world's oceans every year, there is growing concern about the proliferation of plastics in the environment. Despite this, surprisingly little is known about the full impact of plastic pollution on human health.

But a first-of-its-kind study released Tuesday sets out to change that. The study, Plastic & Health: The Hidden Costs of a Plastic Planet, is especially groundbreaking because it looks at the health impacts of every stage in the life cycle of plastics, from the extraction of the fossil fuels that make them to their permanence in the environment. While previous studies have focused on particular products, manufacturing processes or moments in the creation and use of plastics, this study shows that plastics pose serious health risks at every stage in their production, use and disposal.